From 59431ad65437c29a3728f31428363c83e9e4e45c Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Mon, 29 Nov 2021 18:31:37 +0000
Subject: [PATCH] regulator/rpi-panel-attiny: Don't read the LCD power
 status

The I2C to the Atmel is very fussy, and locks up easily on
Pi0-3 particularly on reads.

The LCD power status is controlled solely by this driver, so
rather than reading it back from the Atmel, use the cached
status last set.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/regulator/rpi-panel-attiny-regulator.c | 18 +-----------------
 1 file changed, 1 insertion(+), 17 deletions(-)

--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -144,24 +144,8 @@ static int attiny_lcd_power_disable(stru
 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
 {
 	struct attiny_lcd *state = rdev_get_drvdata(rdev);
-	unsigned int data;
-	int ret, i;
 
-	mutex_lock(&state->lock);
-
-	for (i = 0; i < 10; i++) {
-		ret = regmap_read(rdev->regmap, REG_PORTC, &data);
-		if (!ret)
-			break;
-		usleep_range(10000, 12000);
-	}
-
-	mutex_unlock(&state->lock);
-
-	if (ret < 0)
-		return ret;
-
-	return data & PC_RST_BRIDGE_N;
+	return state->port_states[REG_PORTC - REG_PORTA] & PC_RST_BRIDGE_N;
 }
 
 static const struct regulator_init_data attiny_regulator_default = {
